Spectral scaling technique to determine extreme Carrington‐level geomagnetically induced currents effects

Space weather events produce variations in the electric current in the Earth's magnetosphere and ionosphere. From these high‐altitude atmospheric regions, resulting geomagnetically induced currents (GICs) can lead to fluctuations in ground currents that affect the electric power grid and potentially overload transformers during extreme storms. The most extreme geomagnetic storm on record, known as the 1859 Carrington event, was so intense that ground‐based magnetometers were saturated at high magnetic latitudes. The most reliable, unsaturated observation is the hour resolution data from the Colaba Magnetic Observatory in India. However, higher‐frequency components—fluctuations at second through minute time cadence—to the magnetic field can play a significant role in GIC‐related effects. We present a new method for scaling higher‐frequency observations to create a realistic Carrington‐like event magnetic field model, using modern magnetometer observations. Using the magnetic field model and ground conductivity models, we produce an electric field model. This method can be applied to create similar magnetic and electric field models for studies of GIC effects on power grids.